Jurack, StefanLambers, LeenMehner, KatharinaTaentzer, GabrieleWierse, Gerd2020-06-152020-06-1520091436-9915https://depositonce.tu-berlin.de/handle/11303/11366http://dx.doi.org/10.14279/depositonce-10253Activity diagrams are a well-known means to model the control flow of system behavior. Their expressiveness can be enhanced by using their object flow notation. In addition, we refine activities by pairs of pre- and post-conditions formulated by interrelated object diagrams. To define a clear semantics for refined activity diagrams with object flow, we use a graph transformation approach. Control flow is formalized by sets of transformation rule sequences, while object flow is described by partial dependencies between transformation rules. The theory of algebraic graph transformation can be used to validate the consistency of control and object flows in refined activity diagrams. This approach is illustrated by a simple service-based on-line university calendar.en004 Datenverarbeitung; Informatikactivity diagramsgraph transformationobject flowResearch Paper